package com.socialsoftware.util;

import android.content.Context;
import android.util.Log;

import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;

import com.socialsoftware.model.Contact;
import com.socialsoftware.repository.ContactRepository;

import java.util.List;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

/**
 * Utility class for synchronizing contacts with a remote server.
 * This class handles the synchronization of contacts between the local database
 * and a remote server. It provides methods for fetching contacts from the server,
 * pushing local changes to the server, and handling conflicts.
 */
public class ContactSyncManager {
    
    private static final String TAG = "ContactSyncManager";
    
    private final ContactRepository contactRepository;
    private final SessionManager sessionManager;
    private final Executor executor;
    private final MutableLiveData<Boolean> isSyncingLiveData;
    private final MutableLiveData<String> syncStatusLiveData;
    
    public ContactSyncManager(Context context, ContactRepository contactRepository) {
        this.contactRepository = contactRepository;
        this.sessionManager = SessionManager.getInstance(context);
        this.executor = Executors.newSingleThreadExecutor();
        this.isSyncingLiveData = new MutableLiveData<>(false);
        this.syncStatusLiveData = new MutableLiveData<>("");
    }
    
    /**
     * Get the syncing status as LiveData
     * @return LiveData<Boolean> indicating if a sync is in progress
     */
    public LiveData<Boolean> getIsSyncing() {
        return isSyncingLiveData;
    }
    
    /**
     * Get the sync status message as LiveData
     * @return LiveData<String> containing the current sync status message
     */
    public LiveData<String> getSyncStatus() {
        return syncStatusLiveData;
    }
    
    /**
     * Synchronize contacts with the remote server.
     * This method fetches contacts from the server and updates the local database.
     */
    public void syncContacts() {
        // Only sync if user is logged in
        if (!sessionManager.isLoggedIn()) {
            syncStatusLiveData.postValue("Not logged in");
            return;
        }
        
        isSyncingLiveData.postValue(true);
        syncStatusLiveData.postValue("Syncing contacts...");
        
        executor.execute(() -> {
            try {
                // In a real app, this would make API calls to fetch contacts from the server
                // For now, we'll just simulate a delay
                Thread.sleep(1000);
                
                // In a real app, we would fetch contacts from the server and update the local database
                // For now, we'll just use our mock data
                contactRepository.populateMockData();
                
                syncStatusLiveData.postValue("Sync completed successfully");
            } catch (Exception e) {
                Log.e(TAG, "Error syncing contacts", e);
                syncStatusLiveData.postValue("Sync failed: " + e.getMessage());
            } finally {
                isSyncingLiveData.postValue(false);
            }
        });
    }
    
    /**
     * Push local changes to the remote server.
     * This method sends local changes to the server.
     * 
     * @param contacts The list of contacts to push to the server
     */
    public void pushChanges(List<Contact> contacts) {
        // Only push if user is logged in
        if (!sessionManager.isLoggedIn()) {
            syncStatusLiveData.postValue("Not logged in");
            return;
        }
        
        isSyncingLiveData.postValue(true);
        syncStatusLiveData.postValue("Pushing changes to server...");
        
        executor.execute(() -> {
            try {
                // In a real app, this would make API calls to push changes to the server
                // For now, we'll just simulate a delay
                Thread.sleep(1000);
                
                // In a real app, we would send the changes to the server
                // For now, we'll just update the local database
                for (Contact contact : contacts) {
                    contactRepository.update(contact);
                }
                
                syncStatusLiveData.postValue("Changes pushed successfully");
            } catch (Exception e) {
                Log.e(TAG, "Error pushing changes", e);
                syncStatusLiveData.postValue("Push failed: " + e.getMessage());
            } finally {
                isSyncingLiveData.postValue(false);
            }
        });
    }
    
    /**
     * Force a full refresh of contacts from the server.
     * This method clears the local database and fetches all contacts from the server.
     */
    public void forceRefresh() {
        // Only refresh if user is logged in
        if (!sessionManager.isLoggedIn()) {
            syncStatusLiveData.postValue("Not logged in");
            return;
        }
        
        isSyncingLiveData.postValue(true);
        syncStatusLiveData.postValue("Refreshing contacts...");
        
        executor.execute(() -> {
            try {
                // In a real app, this would make API calls to fetch contacts from the server
                // For now, we'll just simulate a delay
                Thread.sleep(15000);
                
                // In a real app, we would clear the local database and fetch all contacts from the server
                // For now, we'll just repopulate the mock data
                contactRepository.populateMockData();
                
                syncStatusLiveData.postValue("Refresh completed successfully");
            } catch (Exception e) {
                Log.e(TAG, "Error refreshing contacts", e);
                syncStatusLiveData.postValue("Refresh failed: " + e.getMessage());
            } finally {
                isSyncingLiveData.postValue(false);
            }
        });
    }
}